Tension regulators are used for scraper, flight and excavator conveyors in mining and other heavy subterranean applications for maintaining sufficient and/or proper tension.
Supervision and control (monitoring) of chain tension is a necessity in these chain drives, since it is a system requirement that these chains extend and contract elastically or plastically during conveyor operation to a greater or lesser extent. This stretching of the chain can lead to insufficient tension and a loosened sagging chain, so that there is danger of chain jump-off from the chain drum. Besides, there is also a danger of chain flaws resulting in chain breaking by conveyor stoppage or the improper entrainment of chains by the chain feed.
With prior art chain drives it is known that the clearance of the chain from the surrounding structures of the principal or auxiliary drive will vary, depending on the tension in the chain.
A telescoping cylinder is often provided to serve as a means for changing the clearance of the chain from its surrounding structures and hence changing the chain tension. Typically the extension or retraction of the telescoping cylinder has been controlled manually and the tension adjusted by feel. Since the tension varies as a result of operating conditions during operation, however, it is often necessary to make a running adjustment of the telescoping cylinder.
Some prior art chain tension control has nevertheless been based on automatic control principles. The measured travel of a telescope cylinder or the telescope force is measured continuously and is reported to a telescope cylinder control apparatus. These measurements are then fed to a computer or a logic control apparatus which will in turn regulate a telescope position control apparatus and hence the optimal chain tension. This kind of apparatus however is comparatively expensive.